Also, here's how it would look modified to use the internal pull-up resistor on the switch (as mentioned earlier). For this circuit you'd not have any additional resistors on the switch circuit, just wire to the switch and from there to ground.

Any wall wart in the 3 to 5 Volt range will be a safe bet (and somewhat cheap, if you don't have one laying about from an old mobile phone or similar to repurpose).

Just remember if you use something lower than 5V you will need to adjust the size of the current limiting resistors you use for your LEDs down or they'll be dimmer (maybe not a bad thing for a night light, but best to test first). LEDcalc.com can help with the maths.

All the best,Geoff

"There is no problem so bad you can't make it worse"- retired astronaut Chris Hadfield

Yes, as I read it PB3 & PB4 are the inverted output of each other, so while they're both PWM they'll be the same as each other, only out of phase. This is a part of the datasheet that I get stuck in so I reserve the right to be wrong

Geoff

"There is no problem so bad you can't make it worse"- retired astronaut Chris Hadfield